1. Field
One or more embodiments described herein relate to an electric vehicle power conversion system.
2. Description of the Related Art
Various types of power conversion systems have been developed for electric vehicles. One type of power conversion system performs a retrogressive operation, which involves boosting a DC voltage from a main power supply, converting the DC voltage to an AC voltage, and outputting the AC voltage to a motor generator. This system may also perform a regenerative operation, which involves supplying regenerative power of the motor generator to the main power supply, auxiliary devices (e.g., electric power steering, an air conditioner, an ECU, etc.) of an electric vehicle, and/or a DC auxiliary power supply.
In such a system, when power conversion stops (e.g., as a result of an off-operation of an ignition key, a fault, or a vehicle collision or other accident), charges stored in a smoothing condenser, installed between electrodes located between a main circuit, may be forcibly (e.g., actively) discharged within a predetermined time. This forced discharge is performed so that an inter-terminal voltage of the smoothing condenser decreases to a safe voltage level.
In order to perform this operation, the switch element of a discharge circuit may be turned on to forcibly discharge the stored charges of the smoothing condenser through a resistor. However, when the discharge circuit fails, the forced discharge of the smoothing condenser is not performed and the inter-terminal voltage of the smoothing condenser may maintain an unsafe, high-voltage level, even after the predetermined time has elapsed.